An Experimental Study on Soil Pavements using Waste Mine Sludge and Synthetic Fibers

Currently, owing to the presence of large amounts of minerals such as pyrite (FeS₂) and marcasite (FeS) in minerals, acid mine drainage (AMD) is formed in Korea's coal mines. Currently, most of the sludge from processing AMD is reclaimed or used as secondary materials in cement. Road pavements until now were aimed at preventing water infiltration and not reducing the support of the road were thus far considered the best measures to enhance durability; therefore, in most cases, cement concrete or asphalt pavements have been applied. However, these pavements pose various problems, such as the inability of microorganisms to survive underground and soil desertification. One of the countermeasures proposed to remedy these problems is soil–cement pavement. In this research, environmentally safe mine sludge, which has low organic matter and has a soil-like yellowish-red color, is proposed as an admixture of the soil-cement pavement. Further, research was conducted to evaluate the appropriate compressive strength, durability, and environmental threats to using synthetic fibers as countermeasures to solve fissures owing to lack of long-term durability and winter-time freezing/thawing. Thus, the most suitable mixture was determined as 5 wt% of exhausted mine sludge and 0.5 wt% of synthetic fibers of length 20 mm, which satisfies the domestic soil-cement pavement standard requirements of compressive strength of 30 kg/cm² and above and weight loss of 14% and lower after freezing/thawing tests.